Appreciable excited-state absorption (ESA) in U2+:CaF2 and Co2+:ZnSe satura
ble absorbers was measured at lambda = 1.573 mum by optical transmission ve
rsus light fluence curves of 30-40 ns long pulses. The ground- and excited-
state absorption cross-sections obtained were (9.15 +/- 0.3) x 10(-20) and
(3.6 +/- 0.2) x 10(-20) cm(2), respectively, for U2+:CaF2, and (57 +/- 4) x
10(-20) and (12.5 +/- 1) x 10(-20) cm(2) for Co2+:ZnSe. Thus, ESA is not n
egligible in U2+:CaF2 and Co2+:ZnSe, as previously estimated. (C) 2001 Else
vier Science B.V. All rights reserved.